Lectin-based affinity capture for MALDI-MS analysis of bacteria.

Immobilized lectins have now been incorporated into affinity surfaces that can be used to isolate broad classes of samples for mass spectrometric analysis. A carbohydrate and a bacterial species that displays the carbohydrate binding motif were isolated and concentrated out of solutions containing salt, urea, buffers, and other contaminants that are deleterious to MALDI mass spectrometry. Concanavalin A was immobilized to a gold foil via a self-assembled monolayer. Samples in phosphate buffer or urine were applied to the capture surface and allowed to interact. The capture surface was then washed to remove salts and other unbound components and subjected to matrix-assisted laser desorption/ionization on a time-of-flight mass spectrometer. The lectin-derivatized surface allowed samples to be concentrated and readily characterized at relatively low levels.